Project description:PURPOSE: To provide a detailed gene expression profile of the normal postnatal mouse cornea. METHODS: Serial analysis of gene expression (SAGE) was performed on postnatal day (PN)9 and adult mouse (6 week) total corneas. The expression of selected genes was analyzed by in situ hybridization. RESULTS: A total of 64,272 PN9 and 62,206 adult tags were sequenced. Mouse corneal transcriptomes are composed of at least 19,544 and 18,509 unique mRNAs, respectively. One third of the unique tags were expressed at both stages, whereas a third was identified exclusively in PN9 or adult corneas. Three hundred thirty-four PN9 and 339 adult tags were enriched more than fivefold over other published nonocular libraries. Abundant transcripts were associated with metabolic functions, redox activities, and barrier integrity. Three members of the Ly-6/uPAR family whose functions are unknown in the cornea constitute more than 1% of the total mRNA. Aquaporin 5, epithelial membrane protein and glutathione-S-transferase (GST) omega-1, and GST alpha-4 mRNAs were preferentially expressed in distinct corneal epithelial layers, providing new markers for stratification. More than 200 tags were differentially expressed, of which 25 mediate transcription. CONCLUSIONS: In addition to providing a detailed profile of expressed genes in the PN9 and mature mouse cornea, the present SAGE data demonstrate dynamic changes in gene expression after eye opening and provide new probes for exploring corneal epithelial cell stratification, development, and function and for exploring the intricate relationship between programmed and environmentally induced gene expression in the cornea. Keywords: other
Project description:Rett syndrome (RTT) is a neurodevelopmental disorder characterized by developmental regression around 6-18 months after birth, followed by a lifetime of intellectual disability, stereotyped behaviors, and motor deficits. RTT is caused by mutations in MeCP2, a methyl-CpG binding protein that was traditionally believed to repress gene expression. Gene expression studies of individual brain regions, however, have revealed that MeCP2 loss-of-function leads to the subtle activation and repression of its gene targets. However, these results may be confounded by the extensive neuronal cell heterogeneity inherent in these brain structures. To minimalize this issue of heterogeneity, we assessed whether Mecp2-null mice exhibited alterations in gene expression patterns in the striatum, a brain nucleus with relatively homogenous neuronal types and is highly relevant to the motor deficits observed in RTT. Despite the homogeneity of the tissue, the fold-change of the 127 differentially expressed genes we identified remained low with a mean change consistent with other studies. However, many of those genes differentially expressed in the striatum have not been previously identified in gene expression analyses of other brain regions. This suggests therefore that the differential expression of genes following loss of MeCP2 occurs in a tissue, or cell-type specific manner and thus MeCP2 function should be understood in a cellular context. In initiating this study, we reasoned that reducing the number of cell types in a microarray experiment may reveal transcriptional changes that are masked in a whole tissue analysis. We therefore focused on tissues more homogeneous in regards to the diversity of neuronal cell types they contain in order to discern gene expression changes in the absence of MeCP2. We chose to isolate the striatum, a tissue composed predominantly of GABAergic medium spiny neurons (MSNs). The striatum was resected from five symptomatic Mecp2-null (KO) male mice bearing the Bird allele and five wild-type (WT) littermates in a C57BL/6 background. We also isolated liver from the same individuals to serve as a non-neuronal control. RNA was isolated from these tissues, converted to cDNA, and hybridized to a single-channel Affymetrix GeneChip Mouse Exon 1.0 ST array for a total of 20 individual arrays.
Project description:Mecp2 loss-of-function has been associated with altered gene expression in many tissues. We characterized gene expression changes within the hippocampi of 3 different Mecp2 loss-of-function mouse models. These studies were used to identify transcriptional differences between these mutants when the mice are largely asymptomatic (4 weeks of age) or have developed overt phenotypes (9 weeks). Hippocampal expression data from WT (Mecp2+/y), KO (Mecp2-/y), R270X (Mecp2-/y,R270XTg), and G273X (Mecp2-/y,G273XTg) mice at 4 and 9 weeks At total of 32 microarrays were performed: 4 animals of each genotype at both 4 weeks and 9 weeks of age.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:Mecp2 loss-of-function has been associated with altered gene expression in many tissues. We characterized gene expression changes within the hippocampi of 3 different Mecp2 loss-of-function mouse models. These studies were used to identify transcriptional differences between these mutants when the mice are largely asymptomatic (4 weeks of age) or have developed overt phenotypes (9 weeks).
Project description:Rett syndrome (RTT) is a neurodevelopmental disorder characterized by developmental regression around 6-18 months after birth, followed by a lifetime of intellectual disability, stereotyped behaviors, and motor deficits. RTT is caused by mutations in MeCP2, a methyl-CpG binding protein that was traditionally believed to repress gene expression. Gene expression studies of individual brain regions, however, have revealed that MeCP2 loss-of-function leads to the subtle activation and repression of its gene targets. However, these results may be confounded by the extensive neuronal cell heterogeneity inherent in these brain structures. To minimalize this issue of heterogeneity, we assessed whether Mecp2-null mice exhibited alterations in gene expression patterns in the striatum, a brain nucleus with relatively homogenous neuronal types and is highly relevant to the motor deficits observed in RTT. Despite the homogeneity of the tissue, the fold-change of the 127 differentially expressed genes we identified remained low with a mean change consistent with other studies. However, many of those genes differentially expressed in the striatum have not been previously identified in gene expression analyses of other brain regions. This suggests therefore that the differential expression of genes following loss of MeCP2 occurs in a tissue, or cell-type specific manner and thus MeCP2 function should be understood in a cellular context.
Project description:Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.
Project description:PGCs undergo two distinct stages of demethylation before reaching a hypomethylated ground state at E13.5. Stage 1 occurs between E7.25- E9.5 in which PGCs experience a global loss of cytosine methylation. However, discreet loci escape this global loss of methylation and between E10.5-E13.5, stage 2 of demethylation takes place. In this stage these loci are targeted by Tet1 and Tet2 leading to the loss of the remaining methylation and resulting in the epigenetic ground state. Our data shows that Dnmt1 is responsible for maintaining the methylation of loci that escape stage 1 demethylation, and that it functions in a UHRF1 independent manner. Our data further demonstrates that when these loci lose methylation prior to stage 2 it results in early activation of the meiotic program, which leads to precocious differentiation of the germ line resulting in a decreased pool of PGCs in the embryo and subsequent infertility in adult mice.
Project description:The replication timing program, or the order in which DNA is duplicated during S-phase, is associated with various features of chromosome structure and function, including gene expression, histone modifications, and 3-D compartmentalization of chromatin.